My mother has a recently purchased '87 Vanagon Wolfsburg Ed. There is a
noticable and uncomfortable draft of warm air comming from under the dash.
I haven't seen the van, but she claims to be turning off all of the heater
controls. This is more and more annoying as temperatures rise in mid
summer.

Is this a common problem? What's the diagnosis and what's the fix?

Many thanks in advance,

Gordon Smith
Honolulu (Manoa), HI
(The van is in Oregon.)